Taking it slow

  Super-slow-motion is on the rise, with affordable kit capable of shooting 240fps teasy to underestimate how much digital SLR cameras have changed the look of video in fewer than five years. Thanks to a combination of shallow depth of field and the ability to record HD footage, video production has taken on a much more filmic look. DSLRs arenwithout their problems - the primary one being that they were never designed to shoot video in the first place - but these problems are worth overcoming when you consider that the equipment necessary to achieve the same effect with a dedicated video camera could set you back ten times as much. By lowering the entry-level price for shallow depth of field video - which blurs foreground or background objects in order to focus the eye on a specific area of the frame - the DSLR revolution has hugely increased the number of filmmakers using the technique in their work. Some may be using it badly, of course; you now canmove for shallow-depth-of-field videos on Vimeo and YouTube. But at least itanother technique thatwithin everyonereach. Once filmmakers get over finding a new look to play with, it should ease off a little and go back to being one of many approaches you can take to shooting video. Any effect will work in some situations and not others. The key thing is to know what youtrying to achieve and then use the tools available to create the appropriate look. With shallow depth of field reaching saturation point, filmmakers are on the lookout for other newly affordable effects they can add to their arsenal. And the latest kid on the block is super-slow-motion video. Thanks to new cameras bringing down the cost of true HD slow motion, you can expect to see this becoming the next effect that crops up everywhere  Slow motion, of course, is nothing new. But the ability to do it smoothly with a camera costing less than ten grand is the key difference, which is what Sonyrecently announced NEXFS700 brings. Itthe newer, swankier, bigger sibling to the NEX-FS100, which sits somewhere between a DSLR and a pro camcorder. You get the benefits of interchangeable lenses and a larger sensor, but also proper audio capabilities and a slightly less awkward form factor. On paper, the FS700 offers a number of advantages over the FS100, but the biggest standout feature is its ability to shoot up to 240fps video at full 1080p resolution - thatten times faster than standard video. The way video works is by showing enough still images every second to convince the eye that the sequence is moving. This happens somewhere around 20 frames per second; film runs at 24fps, PAL video (which we use in the UK) at 25fps and NTSC video (used in the US) at 29.97fps. With fewer than 20fps, the resulting video will look jerky; add more and it will still appear smooth, although with little extra benefit. For this reason, most cameras shoot at either 24fps, 25fps or 29.97fps at full HD resolution. Itnot uncommon to see affordable (less than £3,000) cameras that can run to twice those frame rates, but usually at the expense of resolution, dropping to 720p instead. For anything faster, you were looking at something like the Red Epic (around £30,000 kitted out) or a Phantom high-speed camera (£30,000 to £100,000 depending on the model). Thatquite a jump. the reason you need more frames is so that you can slow down the footage during postproduction. Shoot 24fps and in ten seconds of footage youhave 240 individual frames. If you record at 48fps, the same ten seconds of footage will contain 480 frames - twice as many. If you then play it back at 24fps, it will last twice as long - 20 seconds - but as the frame rate is still above 20fps, it still appears smooth. This is the key to good-looking slow motion. If you try to slow down footage without having extra frames, it will quickly become a horrible, jerky mess. Depending on the editing application you use, the software may try to invent frames to fill the gap, but ittrying to create information that simply isnthere in the source. It might work up to a point, but the further you push it, the worse itgoing  to look. If you want to do good-looking slow motion, the only real option is to record more frames while shooting and then slow it down in post. What makes SonyNEX-FS700 so interesting is that it can record extremely fast frame rates without sacrificing the resolution of the final image. It will maintain 1080p resolution right up to 240fps. You can push it further, but then youstart losing resolution, so the results may not be worth it. This is from a camera with a price tag under £7,000. Therea catch, though. It canrecord these fast frame rates in real time. Instead, the frames are recorded to a buffer and then transferred to memory card once the buffer is full. This means youlimited in the amount of time you can record in slow motion at any one time. So at 240fps, youget around eight seconds before the buffer is full, or around 16 seconds at 120fps. In both cases, that gives you around 1,920 frames, which would last 80 seconds when played back at 24fps. Since youdealing with very short time frames, the FS700 has a neat trick to help you get the right shot. You can just press Record and get the next eight seconds, whatever it is. It also has an additional mode where it will buffer everything and then keep the previous eight seconds when you hit Record. You can leave it running in this mode, and when you see something interesting has happened, you hit the Record button to keep it. Once yourecorded a burst of high-speed video, you also have to wait while the camera writes this information to the card, so you have to plan your slow-motion shots a little. However, given what you can achieve for the price, these limitations are worth it. When used carefully and appropriately, slow motion can really add something to a film. The real appeal of slow motion is that it lets the viewer see something they simply couldnwith the naked eye. Watching things move and events unfold in extreme slow motion can have a mesmerising effect. Whether wefeel the same about this in a yeartime, when the effect will no doubt be everywhere, remains to be seen, but the exciting thing about digital video is that prices are always coming down. What was expensive to achieve even a year ago can cost next to nothing once advances in technology have kicked in. So keep an eye on whatjust around the corner. Even if it seems expensive now, it could be just another feature on every future camera out there.

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